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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 929 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.126 + 186 =
  2. 2.223 + 459 =
  3. 3.769 + 185 =
  4. 4.476 + 538 =
  5. 5.151 + 122 =
  6. 6.184 + 187 =
  7. 7.257 + 208 =
  8. 8.547 − 277 =
  9. 9.668 + 112 =
  10. 10.773 + 477 =
  11. 11.327 + 196 =
  12. 12.667 − 205 =
  13. 13.583 + 131 =
  14. 14.414 + 301 =
  15. 15.455 + 382 =
  16. 16.626 + 366 =
  17. 17.709 − 491 =
  18. 18.949 − 796 =
  19. 19.719 − 427 =
  20. 20.390 + 588 =
  21. 21.746 + 422 =
  22. 22.645 − 216 =
  23. 23.750 + 433 =
  24. 24.726 + 437 =
  25. 25.211 + 641 =
  26. 26.783 + 503 =
  27. 27.663 + 243 =
  28. 28.851 − 179 =
  29. 29.547 + 518 =
  30. 30.555 − 352 =
  31. 31.559 − 132 =
  32. 32.754 − 593 =
  33. 33.483 + 132 =
  34. 34.322 + 327 =
  35. 35.928 − 231 =
  36. 36.630 + 445 =
  37. 37.394 + 211 =
  38. 38.528 − 381 =
  39. 39.438 − 127 =
  40. 40.158 + 545 =

Answer key

  1. 312
  2. 682
  3. 954
  4. 1014
  5. 273
  6. 371
  7. 465
  8. 270
  9. 780
  10. 1250
  11. 523
  12. 462
  13. 714
  14. 715
  15. 837
  16. 992
  17. 218
  18. 153
  19. 292
  20. 978
  21. 1168
  22. 429
  23. 1183
  24. 1163
  25. 852
  26. 1286
  27. 906
  28. 672
  29. 1065
  30. 203
  31. 427
  32. 161
  33. 615
  34. 649
  35. 697
  36. 1075
  37. 605
  38. 147
  39. 311
  40. 703

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